The invention relates to a pull-out slide for furniture drawers, leaves, or the like. Pull-out slides generally include a guide rail of the pull-out slide fastened to a stationary part, such as the furniture body, and an additional guide rail being fastened to the pull-out furniture part itself. Depending upon the size and the weight of the furniture part to be pulled out, the pull-out slide must absorb vertical forces such as weight of the furniture part. Additionally, the pull-out slide should also ensure a secure lateral guiding.
A pull-out slide of the prior art is disclosed by German Patent Document DE 44 43 063 C1, which shows a first and a third guide profile, each having a general U-shaped construction opening horizontally in the same direction; A second guide rail also has a U-shaped design and opens in the opposite direction, extends between the U-legs of the first and third guide rail. Balls are arranged at both sides of each U-leg of the second guide rail in order to displaceably guide the rail.
The use of balls permits only limited loading since, because of the geometry of the balls, only punctiform contacts exist with the tracks. A flat contact of the balls is eliminated because of the different ball radius relative to the axis of rotation. In addition, because of the limited available space for such pull-out slides, the balls must remain relatively small in order to achieve a favorable surface loading. The space issue was addressed by German Patent Document DE 3127701 A1, which suggests a triangular exterior profile with inside comers having tracks adapted to the diameter of balls. The wall areas of the equilateral triangle forming the inside corners enclose an angle of 60xc2x0, which means that the interior profile also must have an acute-angle construction which necessarily permits only very narrow tracks for the balls on the interior profile.
German Patent Document DE 36 23 743 C2 addresses this shortcoming of the prior art by suggesting a pull-out slide with two rails equipped with cylindrical roller bodies whose center axes extend beyond their faces to form a triangle. In contrast to the use of balls, which lack the ability to spread force over a larger area, the entire length of the cylindrical roller body acts to distribute force on the opposite walls. The outer rail forms a hollow profile and has a downward-directed slot which forms the passage for the second rail. The interior of the hollow profile tapers toward the slot such that two rolling paths of the roller bodies are formed which extend at an acute angle with respect to a vertical line.
The disadvantage of the pull-out slide illustrated in German Patent Document DE 36 23 743 C2 is that the two rolling paths, which extend at an angle with respect to one another, an elastic area will spread apart in a wedge-like manner under the effect of a load. In the pulled-out condition, the weight of the furniture part stresses the front area of the pull-out slide downward. In contrast, the rear area of the pull-out slide experiences greater stress in the upward direction, due to a lever-effect. These opposite-acting stresses induce a spreading of the two rails which affects the horizontal roller body and deforms the outer rail such that the running surface becomes curved with respect to the horizontal roller body. The two effects of the spreading necessarily result in poorer running characteristics and a higher wear of the horizontal roller body.
Recognizing these shortcomings of the prior art, the invention further develops the pull-out slide. The guide rails of the present design will resist deformation under a load, thereby enhancing the good running characteristics of the guide rails under relatively large loads.
This object is achieved by means of a pull-out slide for a telescoping furniture part comprising at least one stationary guide rail fastenable to a stationary furniture part and at least one moving guide rail fastenable to a moving furniture part A bearing unit is positioned to allow relative displacement in a longitudinal direction between the stationary guide rail and the moving guide rail.
A bearing unit has several cylindrical roller bodies held between the two guide rails. Axes of the cylindrical roller bodies are generally perpendicular to the displacement direction. For example, at least one first cylindrical roller body is arranged essentially horizontally between the guide rails. Additionally, third and second cylindrical roller bodies are arranged such that their axes of rotation form a triangle in a plane orthogonal to the direction of displacement.
A guide rail may extend around the roller bodies and the guide rail having the supporting web, and also may have a slot for the guiding-through of the supporting web. Moreover, the pull-out slide may be formed so that one guide rail extends around the other guide rail and around the cylindrical roller bodies.
A supporting web is formed on one of the guide rails; the supporting web engages the triangle formed by the roller bodies on an outer rail. The supporting web may have triangularly arranged running surfaces, each running surface respectively engaging a cylindrical roller body. In this embodiment, the supporting web extends interior of the triangle formed by the roller body axes.
A slot in the outer guide rail; which allows the inner guide rail to pass through, does not extend between the two sloped roller bodies. Rather, it extends approximately laterally horizontally in a less loaded area. Thus, when these roller bodies are loaded, a dimensionally stable guiding of all roller bodies is ensured.
The triangular configuration permits a simple manufacturing of the corresponding guide rail at reasonable cost, for example, by edging a metal part.
Alternatively, the reaching-around guide rail may have a pentagonal cross-section, such that three edges of the pentagon serve as running surfaces and two edges connect two running surfaces with one another. The pentagonal cross-section requires more space than the triangular configuration; therefore, one may select a polygonal cross-section that is suited to the design constraints or preferences of the designer.
Preferably, each bearing unit comprises several roller bodies arranged behind one another in the displacing direction. Increased stability is obtained if a bearing unit has several roller bodies arranged behind one another in the displacing direction because the load can be simultaneously distributed to several roller bodies.
In the two-rail embodiment, as the pull-out is moved to the open position, a bearing unit in the front in the pull-out direction is stressed more vertically downward, while is stressed more vertically upward as a result of the lever effect.
The essentially horizontal arrangement of the roller body in this case comprises smaller angles of slope of up to 15xc2x0, which may be useful for special applications. The angles of slope of the triangle formed by the roller bodies can also be configured because, for example, in the case of an extensive vertical load and a relatively large amount of space, smaller angles of slope are to be preferred.
Preferably, one guide rail reaches around the roller bodies and the guide rail with the supporting web, and correspondingly has a laterally arranged slot for the guiding-through of the supporting web. In this case, the integral construction of the outer guide rail results in a particularly high inherent stability.
In the two rail embodiment, a portion of the pull-out furniture part remains in the furniture body. True, this may limit the maximal running path of the pull-out slide; however, the construction costs are particularly low.
Another embodiment of the invention is a pull-out slide having three guide rails. Specifically, the pull-out slide has a first guide rail connected with the stationary part and a third guide rail connected with the moving furniture part. The pullout slide further has a second guide rail displaceably disposed with respect to both the first guide rail the third guide rail.
The three-rail embodiment referred to in the preceding paragraph may be formed such that the second guide rail has a C-shaped cross-section and is provided with one bend on each of two free legs of the C-shape. In this embodiment, running surfaces engaging the sloped roller bodies are formed on the bends. Additionally, the two free legs of the second guide rail form one running surface respectively for a horizontally arranged cylindrical roller body and may be connected with one another by a connecting web.
In the three-rail embodiment, a cylindrical roller body may be disposed on the connecting web to contact the first guide rail and the third guide rail at a circumference of the cylindrical roller body.
The three-rail embodiment permits a pulling-out of the furniture part beyond the furniture body. It is also possible to use four or more guide rails so that the maximal running course of the pull-out piece is enlarged.
A compact construction of the embodiment with three guide rails is obtained if the second guide rail has a C-shaped construction and its two free legs are each provided with a bend, on which the running surfaces for the sloped roller bodies are constructed. In this case, the two free legs of the second guide rail each form a running surface for a horizontally arranged roller body and are connected with one another by way of a connecting web, so that only a minimal number of individual components are required for the pull-out slide.
If a roller which, on its circumference, is in contact with the first guide rail and the third guide rail is disposed at the above-mentioned connecting web, a uniform movement of the third and second guide rails relative to the first guide rail is obtained in a simple manner.
In the embodiments with three or more guide rails, the shape of the guide rails can be varied according to the available space and the stress to be expected, in which case the second guide rail or the center guide rails, according to the available space and the respective load, may preferably have a Z-shaped, X-shaped, E-shaped or S-shaped construction.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.